In order to join together devices, for example attachment of different kinds of panels in vehicles, screw joint reinforcements have earlier traditionally been used. However, screw joint reinforcements suffer from a number of disadvantages. The head of the screw will remain visible after attachment and should in some way be hidden or a less aesthetic appearance of the installation must be accepted. Furthermore, the mounting of a screw joint reinforcement is time consuming. In addition, such a mounting must be made manually why the use of a screw joint reinforcement in a manufacturing process is an obstacle concerning an automatization of the process.
An increased interest in reducing mounting time and enabling automatization of the mounting has encouraged the search for alternatives to screw joint reinforcements. Resilient fastening devices, usually called clips, have therefore been set out to be used for certain purposes. Clips are available in a numerous of different models and different materials. A kind of fastening devices which are commonly used is a two part fastening device made by a plastic material having a male and a female part for snap fitting with each other and each one provided with means for attachment in a panel and a part of the car, respectively. The use of such resilient fastening devices solves at least partly the above described problems concerning the aesthetic appearance. In order to further improve the performance and shorten the mounting time it has been common practice to use fastening devices which only comprise one part, so called “one-piece fasteners”. Clips of this kind, which work perfectly well, are cheap and easy to mount and are thus requested today, mainly in the automotive industry but also in other kind of industry having a desire to attach parts to each other or attach safety panels and this kind of fastening devices are thus desired in order to make a production process more efficient.
However, there are several problems associated with the manufacturing of these clips today in accordance with the demands from the users who require that the clips shall be user friendly designed and easy to mount while at the same time they shall not detach once they are put in their proper place. The clips shall also be cheap which implies the requirement that they shall be easy to manufacture. In addition, they shall preferably only comprise one part, and not having a second part which is manufactured and adapted to be an anchor to be safely attached to as was common earlier, which implies that the clips only comprising one part must be able to be put in place and provide a desired attachment strength in prefabricated hole which may have rather large tolerances. It is also a risk that such holes have sharp edges which may damage the clip or make the insertion of the clip in the hole more difficult such that the clip may be askew and thus will be subject to an extra force in order to be able to place the clip in its intended position.
A frequently method used today for the manufacturing of a clip is to produce them by compression moulding or die-casting using a plastic material. The demand that this shall be possible to perform in a cheap and cost effective way implies that the clip may not have too complicated geometries and it shall be possible to mould it in a one-step-process. The production is further complicated due to the fact that the clips are rather small (a standard diameter for a mounting hole in the automotive industry today is 8 mm) which makes it difficult to fill out small cavities in a mould and to get rid of excess material if the design not support this. Further requirements of the clips are that they shall be robust, not only in the sense of staying in its position, but also that they shall also withstand the mounting procedure in a good way and not be damaged by for example an impact which may break it or weaken it at the time of mounting if it is not correctly inserted or is handled carelessly. In order to avoid such handling of the clip at mounting is it important that the insertion force resistance is not too large.
There are a number of known fastening devices (clips) which are used to attach different elements to each other which intend to comply with one or several of the above desires. In U.S. Pat. No. 6,752,950 is a clip described which is made by using two materials in order to provide the desired properties. However, this implies a fairly complicated process for manufacturing and it implies the clip needs a longer time to be produced and a more time consuming process. In U.S. Pat. No. 3,905,270 is described a clip which is manufactured by injection moulding and has a geometry provided with three spring legs in order to assure a reliable insertion into, and attachment to, the hole. This clip is designed to be able to be manufactured in an easy way and to be attached safely. However, experience has shown that this kind of clips are fairly easy damaged if it is inserted askew and one of the spring legs may be damaged if it is located askew or subject to a too large force during insertion. In U.S. Pat. No. 5,301,396 it is proposed to make the insertion of the clip into a hole easier by adding a ring through which the clip must be pressed when it shall be attached to a hole which thus helps to facilitate that the clip easily may be put in its position without being damaged. However, this solution implies the need of an extra part in order to attach the clip and render manufacturing and attachment more complicated since two parts are needed. Further examples of clips are disclosed in U.S. Pat. No. 3,177,540 in which a number of flexible flanges are compressed when inserted in a hole. Also GB 2,026,083 shows a clip which is intended to in an easy way be fitted in a round hole by being provided with a number of flanges, for example 3, which shall guide and locate the clip such that it is positioned in its desired position so as to attach two parts in a confident way.
All these clips disclose different solutions of how different kinds of clips may be designed and different solutions concerning clips of today. However, these clips are not considered to be of the desired quality and/or not being easy enough to handle when mounting why there is a remaining desire of an improved clip which is easy to manufacture and mount, preferably a one-piece-clip, and provides a secure mounting with a reduced risk of being damaged or to break at mounting.